Method and apparatus for the freeform growth of three-dimensional structures using pressurized precursor flows and growth rate control

摘要

Method and apparatus for the selective heat-induced deposition of solid material from gas-phase or super-critical fluids to produce three- dimensional parts by pyrolysis of the fluids. The apparatus involves computer/feedback control of the evolving shape by direct monitoring of the volumetric deposition rate or growth profile, and modifying light beam focal properties, the position and orientation of the deposit relative to the beam foci, and/or the pressure and flow of reactants to the growth zone. The precursor gases may be pressurized and heated to the critical point or beyond, becoming super-critical fluids, without condensation. Growth occurs by diffusion of reactants to the growth zone through a boundary layer over the deposit. One method of growth includes directing a large-area impinging jet of precursor fluid(s) onto a deposit interface, while limiting the reaction zone to a smaller area determined solely by size of the heated zone (through use of a radiant beam, e.g.). Another method comprises directing a small-area impinging jet of precursor fluid onto a deposit interface, where the heated region is larger than the jet size. Inclusion of a powder admixture and a precursor as a reactant, flowed jointly at high-pressures, create a two- phase flow, facilitated by increased viscosity of precursor fluid at high pressures. The powder may also be flowed separately, and adds volume and properties to the deposit material. Thus, the invention allows continuous growth of single- or multi-material, three-dimensional microstructures with internal features and characteristic dimensions from microns to decimeters.